1. Field of the Invention
The present invention relates to solid circular dielectric waveguides, but in particular, the present invention relates to a method of increasing the power output of a solid circular dielectric waveguide without substantially effecting its electromagnetic properties.
2. Description of the Prior Art
The present invention is concerned with circular dielectric waveguides for use at millimeter wavelengths [1], [2]. Typical values of wavelength are 1 to 10 mm, with corresponding frequencies between 300 and 30 GHz. The waveguides in question are typically dielectric cylinders a few millimeters in diameter. Typical materials are polytetrafluoroethylene (PTFE) (which is also known as "TEFLON", a trademark of the E.I. du Pont de Nemours & Company, Inc.), polystyrene, and fused quartz.
The waveguides are typically operated in a "single hybrid mode" situation in which only one electromagnetic mode can propagate. This dominant mode is known as the HE.sub.11 mode. To ensure single mode operation, the diameter of the waveguide must be kept below a certain critical value which depends on the frequency of the guided wave and the dielectric constant of the guide.
Dielectric waveguides have traditionally been made to have very smooth surfaces in order to eliminate the possibility of radiating electromagnetic signals in an undesirable fashion. However, Marcuse [3] and Marcuse, et al [4] have shown that there are situations were imperfections do not result in undesirable radiation. Consequently, there has been considerable study of the electromagnetic properties of dielectric waveguides; however, there has been little mention in the prior art of the power-handling capabilities of dielectric waveguides. This is not surprising, as dielectric waveguides are primarily of interest at millimeter wavelengths, where levels of available power are rather low. In the recent past and at the present time, the amount of activity aimed at developing high-power millimeter wavelength sources has increased. Thus, there is a need in the prior art to increase the power-handling capability of circular dielectric waveguides without substantially effecting their normal electromagnetic properties and operation.
The prior art, as indicated hereinabove, includes some progress in the study and implementation of solid circular dielectric waveguides. However, insofar as can be determined, no prior art dielectric waveguide or method incorporates all of the features and advantages of the present invention.